Atomizer for liquid fuel

ABSTRACT

An atomizer for liquids of the type utilizing atomization by a gas is provided with at least two channels which terminate at the head of the atomizer and which communicate with a common supply for the gas. The channels pass through a common, bounded space and at the location of the intersections around their entire circumference communicate with that space. The bounded space communicates with a supply for the liquid.

United States Patent 1191 3,747,860 Habers July 24, 1973 [54] ATOMIZERFOR LIQUID FUEL 1,727,464 9/1929 Debus 239/433 2,192,996 3/1940 Fenzl239/431 [751 mammwlhelmls Babe", Amsterdam, 2,414,459 1/1947 Fletcher239/429 Netherlands 3,072,344 1/1963 McKenzie 239/433 Assignee: C p y,New Y Carkm et a]. [22] Filed: 1971 Primary Examiner--Lloyd L. King 211App], 192 117 Attorney-Harold L. Denkler et al.

[30] Foreign Application Priority Data [57] ABSTRACT Oct. 26, 1970Netherlands 7015687 All atomizer for liquidS Ofthe yp utilizingatomization by a gas is provided with at least two channels which 52U.S. CI. 239/431, 239/433 terminate at the head of the atomizer andwhich 51 Int. c1 B051) 7/06 municate with a common pp y for the Thechan- [58] Field 6: Search 239/429, 430, 431, p through a common,bounded space a at the 239 432 433 location of the intersections aroundtheir entire circumference communicate with that space. The [56]References Cit d bounded space communicates with a supply for the liq-UNITED STATES PATENTS 7l6,724 12/1902 Lassoe et a1. 239/431 X 10 Claims,5 Drawing Figures PAIENIEmmz-mn 3.741.

v sum 3 or 3 I B v i 4 6 1 5 FIG.4

ATOMIZER FOR LIQUID FUEL BACKGROUND OF THE INVENTION 1. Field of theInvention The invention relates to an atomizer for liquids, includingdispersions of solid particles in a liquid and emulsions.

2. Description of the Prior Art Atomizers are applied on a large scalein combustion engineering. Liquid fuel is often divided into very smalldroplets in an atomizer prior to being mixed with air in a combustionchamber. Atomization is generally effected by providing for the liquidto spurt under pressure from one or more openings of special shape anddimensions. The addition of a gas, for instance steam, improves theatomization. It'is of importance to have available atomizers which arecapable of accommodating to large variations in fuel supply whilemaintaining desired combustion properties and with minimum steamconsumption. Although the elucidation to be given hereinafter will'dealmainly with steam atomization of oil, the atomizer is not restrictedthereto. Steam may be replaced by, for instance, air, natural gas,refinery gas, etc. The steam may also be somewhat wet. The atomizer canalso be applied in spraying installations, for instance, for the purposeof the vaporization of a volatile component.

SUMMARY OF THE INVENTION According to the invention, an atomizer forliquids of the type utilizing atomization by a gas is provided with atleast two channels which terminate at the head of the atomizer and whichcommunicate with a common supply for the gas. The channels pass througha common, bounded space and at the location of the intersections aroundtheir entire circumference communicate with that space, which spacecommunicates with a supply for the liquid.

Thus, passingas from inside the atomizer to the outlets of the channels,at first only steam is passed through the channels. At the locations ofthe intersections of the channels with the common bounded space, oilenters into the channels. This entry at those locations takes placearound the entire circumference of the channels, which for this purposehave been interrupted there. By adjustment of the pressures on the oilsupply and on the steam supply the ratio between oil and steam can bedetermined. By providing for all channels to pass through one common oilspace'stable operation is ensured and a simple construction becomespossible.

Experiments to be mentioned hereinafter have revealed that with thisatomizer a surprisingly small quantity of steam is required forobtaining a very good atomization. A good atomization is promoted if theliquid space is bounded mainly by two surfaces which are parallel toeach other and at a short distance from each other. The liquidspace mayverysuitably be annular and in a coaxial position relative to theatomizer. The annular liquid space may form a hollow cylinder or mayform a hollow cone, both being in a coaxial position relative to theatomizer. The aperture of the hollow cone may be directed away from thehead of the atomizer. The liquid space may also have the shape of a flatbox whose bounding flat faces are perpendicular to the centre line ofthe atomizer.

The flow pattern of the oil in the narrow annular or box-shaped commonspace guarantees a good atomization. The width of the gap may amount to0.5-2.0 mm. At the location where a channel around its entirecircumference communicates with the oil space, the steam jet meets anoil film which enters around the entire circumference of the channel.Due to this omnidirectional flow and due to the small thickness of theoil film, the oil film as soon as it joins the steam, is easily andevenly divided into droplets which split into even finer dropletsleaving the outlets of the channels. Apart from the very low steamconsumption already mentioned the additional advantage of a simpleconstruction of the atomizer and of easy maintenance is achieved. Thiswill be further elucidated when discussing the figures.

The outlets of the channels may be evenly arranged around the centralaxis of the atomizer, for instance in one or more circles. The channelsmay be situated in the plane of the lateral face of a body of revolutionwith the center line of the atomizer as the axis of rotation. That bodyof revolution may be a hollow cone with the base directed towards thehead of the atomizer, i.e., upwardly when the atomizer is in a verticalposition with the head to the top. Suitable atomizers, for large to verylarge capacities, may be provided, for example, with 6-12 channels.Owing to the above-mentioned configurations flames of a regular shapecan be obtained. Of course, the way in which the combustion air issupplied and the shape of the burner throat as a matter of fact play animportant roll.

It is of importance that the section of each channel between the liquidspace and the outlet has a larger diameter than the remaining section ofthat channel, for instance, about 1.5 times as large. In this section ofchannel sufficient volume will'then be available for the mixture ofsteam and oil droplets which is formed at the intersection.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a sectional view of anembodiment of the atomizer of this invention having a cylindrical commonbounded liquid space.

FIG. 2 is a sectional view of an embodiment of the atomizer of thisinvention having a conical bounded common liquid space.

FIG. 3 is a top view of the apparatus of FIG. 2.

FIG. 4 is a sectional view of an embodiment of the atomizer of thisinvention having a box-shaped common bounded liquid space.

FIG. 5 is a top view of the apparatus of FIG. 4.

DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 is a cross-sectional view ofan atomizer with an annular liquid space that forms a hollow cylinder.On an outer tube 1 there is positioned an unscrewable head 2. A tubesection 3 affixed to the head 2 matingly engages an inner tube 4. Theinner tube 4 contains a steam channel 5 which terminates in the tubesection 3. An annular space 6 between the outer tube 1 and the tube 3serves as the oil supply. This space 6 ends in an annular space 7. Thisspace 7 forms a hollow cylinder which, together with at least twochannels 8 passing through the wall of the tube section 3 and the head 2constitutes the essence of the invention. The cylindrical bounding wallsof the space 7 are close to each other. The channels 8 pass through thatspace and communicate with it around their entire circumference. This ispossible because the space 7 extends beyond the intersection with thechannels 8. The channels 8 are wider beyond the space 7 where they passthrough the head 2 than before it. They terminate at 9. The outlets 9are preferably disposed in a circular pattern around the center line ofthe atomizer. The arrow 10 denotes the supply of the steam, the arrows11 that of the oil.

The apex of the cone formed by the atomized oil amounts to about 75.This angle can also be larger or smaller.

Because of its simplicity of construction the atomizer described caneasily be mounted and made free from leaks. This is important because inburners high pressures are of ten applied, in particular when burningheavy oils. Moreover, the liquid space and the channels can easily beinspected and cleaned. By removing the unscrewable head 2 the liquidspace 7 is exposed completely and the channels 8 are readily accessible.

FIG. 2 shows a cross-sectional view of an atomizer with an annularliquid space 7 that forms a hollow cone. Numbers in this and in the nextfigure that have been used earlier represent the same parts as denotedby them before. In this embodiment, the advantages as discussed withFIG. 1 remain. In FIG. 3 half of the top view of the atomizer of FIG. 2is represented.

FIG. 4 gives a cross-section of an atomizer with a box-shaped liquidspace. The box-shaped space 7" is formed by the top face of the innertube 4, and the bottom of a head piece 12. The head piece 12 is forcedtight by means of a coupling nut 13. Besides the channels 8" passingthrough inner tube 4 and head piece 12 in a manner similar to thechannel 8 of FIG. 1, another central channel 14 with outlet 15 ispresent here. This atomizer also can be dismounted and cleaned easily.

EXAMPLES A burner provided with an atomizer according to the invention,in particular approximately according to FIG. 2, was constructed for amaximum fuel consumption of 1500 kg/h of fuel oil. The burner wasprovided with six channels. The burner was found to operate well over avery wide fuel consumption range, namely from 120 up to 1200 kg/h ofoil. The quantity of steam was dependent both on the fuel consumptionand on the steam pressure which was kept constant here at 13.5 atm. With120 kg/h of oil, 65 kg/h of steam was found to be required and with 1500kg/h of oil only 19 kg/h (1.25 percent). This is exceptionally low and,as a result, a substantial reduction in costs is obtained.

Flame stability was always good. No carbon deposits were found on thehead. Nor was fouling of the channels and spaces in the atomizerobserved, not even after burning heavy fuel oil.

Reduction of the steam consumption at low loads can be achieved byproviding for the steam supply to be throttled down together with thefuel supply. This provision makes the installation more expensive,however, and in view of the steam consumption being low already issuperfluous with this burner. If the combustion air is controlled so asto follow the fuel consumption, then the fuel supply can be throttledown by a factor of 10 without objections.

A burner provided with an atomizer approximately according to FIG. 1,with 10 channels, was constructed for a maximum consumption on 2000 kg/hof fuel oil.

With this burner, too, the same favorable results were achieved as withthe burner described hereinbefore. It was found that the fuelconsumption could be varied by a factor of 10 and a minimum steamconsumption of only 1.25 percent w at an oil consumption of 2000kg/hcould be attained.

I claim as my invention 1. An atomizer for liquids comprising:

an atomizer head having a plurality of fluid outlets for atomized liquidtherein;

at least two channels within the atomizer, each channel terminating atan outlet in the atomizer head and being in fluid communication with acommon gas supply channel;

the atomizer head having a bounded space therein in fluid communicationwith a supply of liquid to be atomized;

the channels intersecting and passing through said bounded space, thesection of each channel between the bounded space and the outlet of theatomizer being of a larger diameter than the section of each channelbetween the bounded space and the common gas supply channel; and

each of the channels communicating with the bounded space around theentire perimeter of the channel at the location of the intersection ofthe channel with the bounded space;

whereby gas flowing from the common gas supply passes into the channels,contacts and atomizes liquid at-the intersection of the channels withthe bounded space, and carries atomized liquid further down the channelsto the fluid outlets.

2. An atomizer according to claim 1, wherein the bounded space isbounded by two surfaces which are parallel to each other and at a shortdistance from each other.

3. An atomizer according to claim 2, wherein the bounded space isannular and in a coaxial position relative to the central axis of theatomizer.

4. An atomizer according to claim 3, wherein the annular bounded spaceforms a hollow cylinder.

5. An atomizer according to claim 3, wherein the annular bounded spaceforms a hollow cone, the apex of the hollow cone being axially directedin the direction of flow of atomized liquid.

6. An atomizer according to claim 3, wherein the bounded space has theshape of a flat box, having bounding flat faces perpendicular to thecentral axis of the atomizer.

7. An atomizer according to claim 3, in which atomizer the fluid outletsare evenly arranged around the central axis of the atomizer.

8. An atomizer according to claim 1, in which atomizer the channels aresituated in the plane of the lateral face of a body of revolution withthe central axis of the atomizer as the axis of rotation.

9. An atomizer according to claim 8, in which atomizer the body ofrevolution is a hollow cone with the base directed in the direction offlow of atomized liquid.

10. An atomizer according to claim 1, in which atomizer the diameter ofthe section between the bounded space and the outlet is about 1.5 timesas large as that of the section between the gas supply and the boundedspace.

* i 1 i i

1. An atomizer for liquids comprising: an atomizer head having aplurality of fluid outlets for atomized liquid therein; at least twochannels within the atomizer, each channel terminating at an outlet inthe atomizer head and being in fluid communication with a common gassupply channel; the atomizer head having a bounded space therein influid communication with a supply of liquid to be atomized; the channelsintersecting and passing through said bounded space, the section of eachchannel between the bounded space and the outlet of the atomizer beingof a larger diameter than the section of each channel between thebounded space and the common gas supply channel; and each of thechannels communicating with the bounded space around the entireperimeter of the channel at the location of the intersection of thechannel with the bounded space; whereby gas flowing from the common gassupply passes into the channels, contacts and atomizes liquid at theintersection of the channels with the bounded space, and carriesatomized liquid further down the channels to the fluid outlets.
 2. Anatomizer according to claim 1, wherein the bounded space is bounded bytwo surfaces which are parallel to each other and at a short distancefrom each other.
 3. An atomizer according to claim 2, wherein thebounded space is annular and in a coaxial position relative to thecentral axis of the atomizer.
 4. An atomizer according to claim 3,wherein the annular bounded space forms a hollow cylinder.
 5. Anatomizer according to claim 3, wherein the annular bounded space forms ahollow cone, the apex of the hollow cone being axially directed in thedirection of flow of atomized liquid.
 6. An atomizer according to claim3, wherein the bounded space has the shape of a flat box, havingbounding flat faces perpendicular to the central axis of the atomizer.7. An atomizer according to claim 3, in which atomizer the fluid outletsare evenly arranged around the central axis of the atomizer.
 8. Anatomizer according to claim 1, in which atomizer the channels aresituated in the plane of the lateral face of a body of revolution withthe central axis of the atomizer as the axis of rotation.
 9. An atomizeraccording to claim 8, in which atomizer the body of revolution is ahollow cone with the base directed in the direction of flow of atomizedliquid.
 10. An atomizer according to claim 1, in which atomizer thediameter of the section between the bounded space and the outlet isabout 1.5 times as large as that of the section between the gas supplyand the bounded space.